Terrell Davis '100% Bought In On Sean Payton,' Insists Russell Wilson Isn't Washed

Huge endorsement for Sean Payton ... Broncos legend, Terrell Davis says he believes Denver absolutely hired the right man when it made him its new head coach this offseason -- telling TMZ Sports he's "100 percent bought in" on the guy.

The former NFL tailback talked all things Broncos with us out at Super Bowl week earlier this month ... and he gushed over Nathaniel Hackett's replacement -- saying the former Saints coach's resume has blown him away.

So much so, Davis believes he can turn the ship around in Denver quickly -- and help struggling QB Russell Wilson in the process.

"He's got built-in equity," Davis said of Payton. I've already seen what he can do with quarterbacks which leads me to be very positive in what he can do with Russell Wilson."

As for the state of Russ' game ... Davis told us he doesn't think the quarterback is washed at all.

Instead, he said he thinks the pieces around Wilson -- and the former system he was in -- didn't do much to highlight his strengths.

"He's not washed. He's not broken," Davis said of the ex-Seahawks signal-caller. "But obviously, when you have a surrounding support system that doesn't support what you do well, it will expose your flaws."

That's when Davis reiterated he fully believes Payton can help him with all of that.

Davis also spoke with us about the criticism Russ has received over his social media presence since joining Denver -- and while the Hall of Famer said most of it is completely unfounded ... he did advise the 33-year-old to tamp things down a bit on his Twitter and Instagram.

"Let's back off this a lil' bit and then let's go show them -- and I don't mean on social media," the three-time Pro Bowler said.